Nucleus nervi trochlearis
The Nucleus nervi trochlearis ("Trochlearis nucleus") is a bilateral core area ( nucleus ) from which the Nervus trochlearis ( cranial nerve IV) originates. Together with the nucleus nervi oculomotorii , the Edinger-Westphal nucleus and the nucleus motorius nervi abducentis, it belongs to the eye muscle nuclei that are connected to one another via the medial longitudinal bundle ( Fasciculus longitudinalis medialis ).
The nucleus nervi trochlearis lies in the posterior part of the midbrain dome ( tegmentum mesencephali ), approximately at the level of the colliculi inferiores . Its nerve cells receive impulses from the cerebral cortex on the same side . The nerve fibers emanating from the core area run dorsally around the central gray cave and cross above the fourth cerebral ventricle to the other (contralateral) side. In the area of the brain stem , the nerve fibers emerge from the brain as the trochlear nerve. Due to the complete crossing of the efferents , the left trochlear core is responsible for the right superior obliquus muscle (see also: contralaterality of the forebrain ).
If this core area is damaged, on the other side (contralateral), the eyeball is misaligned upwards, medially and externally, as the fibers cross completely to the other side after they exit. Damage to the trochlear nerve itself causes the same symptoms on the same (ipsilateral) side.
literature
- Farhang Samandari, Dieter Reissig: Functional anatomy of the cranial nerves and the vegetative nervous system. For doctors and dentists. 2nd, completely revised edition. Walter de Gruyter, Berlin et al.1994, ISBN 3-11-013006-8 , p. 18.
- Martin Trepel: Neuroanatomy. Structure and function. 4th, revised edition. Elsevier, Urban & Fischer, Munich 2008, ISBN 978-3-437-41298-1 .